Generally speaking, tricycle vehicles are sometimes run on unpaved land such as a sandy land or a field, as well as on smooth paved surfaces. Also when the tricycle vehicle runs uphill or climbs a hill, its driver must shift his weight forward along the vehicular body to accordingly shift the center of gravity forward so that the vehicle may be held stable.
In tricycle vehicles according to the prior art, however, the front edge of a seat is extended only as far as a position generally above the foot rests, and a fuel tank is disposed one step above the front of the seat's front edge. Consequently, the driver has found it difficult to shift his weight forward, in order to take a proper driving position in accordance with the road condition. Since, moreover, an engine has its crankcase disposed inside of the foot rests, the width defined by the foot rests becomes excessive. As a result, the driver sometimes cannot fix his lower body in a proper position. Still worse, especially in the case of runs on a field, the foot rests may strike rocks or other impediments of the road, thereby threatening the running stability of the vehicle.